1. Field of the Invention
The present invention generally relates to connectors and connector devices, and more particularly to a connector capable of high-speed transmission and suited for use in electrically connecting a daughter board to a backplane of a communication equipment such as a server, and to a connector device having such a connector.
2. Description of the Related Art
A communication equipment, such as a server, includes a backplane (or backplane board), and a plurality of daughter boards that are arranged in parallel to each other and arranged perpendicularly to the backplane. The plurality of daughter boards are mutually connected via the backplane. Such a structure made up of the backplane and the plurality of daughter boards will hereinafter be referred to as a “printed circuit board combination”.
A backplane connector is mounted at an end of the backplane, and daughter board connectors are mounted at ends of the daughter boards. The daughter boards are connected to the backplane by connecting the daughter board connectors to the backplane connector.
Recently, the signal transmission speed (or data rate) has increased considerably, and the balanced transmission technique is popularly used. The balanced transmission technique transmits a pair of positive and negative signals having the same magnitude with respect to a reference level, so that the signal to be transmitted is uneasily affected by noise. The connectors described above are also designed to enable such a signal transmission using the balanced transmission technique.
FIG. 1 is a perspective view generally showing an example of a conventional connector device. A connector device 10 shown in FIG. 1 is applied to a Printed Circuit Board (PCB) combination 1. FIG. 2 is a perspective view generally showing the connector device 10 shown in FIG. 1 in a state applied to the PCB combination 1.
A backplane 2 and a daughter board 3 shown in FIG. 2 are PCBs. The backplane 2 is located on an XY-plane, while the daughter board 3 is located on an XZ-plane.
A backplane connector 11 and a daughter board connector 21 shown in FIG. 1 both have right-angled transmission paths, as will be described later. The backplane connector 11 and the daughter board connector 21 in combination form the connector device 10. FIG. 1 shows the backplane connector 11 and the daughter board connector 21 in respective connecting positions. The height of the backplane connector 11 and the width of the daughter board connector 21 are taken along the direction Y. The width of the backplane connector 11 and the height of the daughter board connector 21 are taken along the direction Z.
The backplane connector 11 has four contact modules 12-1 through 12-4 which are arranged within a housing (not shown) with a shield plate (not shown) interposed between two adjacent contact modules. Each of the contact modules 12-1 through 12-4 has a main body 13 which is made of a synthetic resin and has a flat shape. Four right-angled transmission path patterns 14-1-1 through 14-1-4 are provided side by side on the main body 13. A male contact part 15 is provided on one end of each of the transmission path patterns 14-1-1 through 14-1-4, and a terminal member 16 is provided on the other end, that is, the base portion of each of the transmission path patterns 14-1-1 through 14-1-4. The male contact parts 15 are disposed in a matrix arrangement at a connecting surface 17 of the backplane connector 11. In each of the contact modules 12-1 through 12-4, the male contact parts 15 are aligned in the direction Y, that is, the direction in which the height of the backplane connector 11 is taken A more detailed description on the backplane connector 11 will be given later in the specification.
The daughter board connector 21 has a structure corresponding to the structure of the backplane connector 11. The daughter board connector 21 has a plurality of contact modules 22-1 through 22-4 which are arranged within a housing (not shown) with a shield plate (not shown) interposed between two adjacent contact modules 22. Each of the contact modules 22-1 through 22-4 has a main body 23 which is made of a synthetic resin and has a flat shape. Four right-angled transmission path patterns 24-1-1 through 24-1-4 are provided side by side on the main body 23. A female contact part 25 is provided on one end of each of the transmission path patterns 24-1-1 through 24-1-4, and a terminal member 26 is provided on the other end, that is, the base portion of each of the transmission path patterns 24-1-1 through 24-1-4. The female contact parts 25 are disposed in a matrix arrangement at a connecting surface 27 of the daughter board connector 21. In each of the contact modules 22-1 through 22-4, the female contact parts 25 are aligned in the direction Z.
As shown in FIG. 2, the terminal members 16 of the backplane connector 11 are mounted on the backplane 2, and the connecting surface 17 is provided at the end of the backplane 2. The terminal members 26 of the daughter board connector 21 are mounted on the daughter board 3, and the connecting surface 27 is provided at the end of the daughter board 3.
The connecting surface 27 of the daughter board connector 21 is made to confront the connecting surface 17 of the backplane connector 11, and the female contact members 25 are connected to the corresponding male contact parts 15, in order to connect the daughter board connector 21 to the backplane connector 11.
In the connector device 10, the contact modules 12-1 through 12-4 of the backplane connector 11 are located on the XY-plane, the contact modules 22-1 through 22-4 of the daughter board connector 21 are located on the XZ-plane, and the contact modules 12-1 through 12-4 of the backplane connector 11 are perpendicular to the contact modules 22-1 through 22-4 of the daughter board connector 21. In other words, each of the contact modules 12-1 through 12-4 of the backplane connector 11 intersects all of the contact modules 22-1 through 22-4 of the daughter board connector 21. Each of the contact modules 22-1 through 22-4 of the daughter board connector 21 intersects all of the contact modules 12-1 through 12-4 of the backplane connector 11.
The applicants are aware of a Japanese Patent Application Publication No. 2005-522012.
When a signal pair is transmitted from the backplane 2 to the daughter board 3 via the connector device 10, a pair of signals is transmitted via the following paths within the connector device 10.
As shown generally in FIG. 2, a pair of signals S1a and S1b from the back plane 2 towards the daughter board 3 is transmitted via a pair of adjacent transmission path patterns 14-1-1 and 14-1-2 of the contact module 12-1 of the backplane connector 11. The signal S1a transmitted via the transmission path pattern 14-1-1 is transmitted via the transmission path pattern 24-1-1 of the contact module 22-1 of the daughter board connector 21, and the signal S1b transmitted via the transmission path pattern 14-1-2 is transmitted via the transmission path pattern 24-2-1 of the contact module 22-2 of the daughter board connector 21.
Another pair of signals S2a and S2b from the back plane 2 towards the daughter board 3 is transmitted via another pair of adjacent transmission path patterns 14-1-3 and 14-1-4 of the contact module 12-1 of the backplane connector 11. The signal S2a transmitted via the transmission path pattern 14-1-3 is transmitted via the transmission path pattern of the contact module 22-3 of the daughter board connector 21, and the signal S2b transmitted via the transmission path pattern 14-1-4 is transmitted via the transmission path pattern of the contact module 22-4 of the daughter board connector 21.
Accordingly, the pair of signals transmitted via the pair of adjacent transmission path patterns of one contact module of the backplane connector is transmitted via the pair of adjacent transmission path patterns of two different contact modules of the daughter board connector.
The pair of signals have waveforms that are closely related to each other, and it is important to maintain this relationship in order to maintain a satisfactory signal transmission characteristic. But when the pair of signals is transmitted via the transmission path patterns of different contact modules within the connector device, the length of the transmission path becomes different for the pair of signals, and the relationship described above cannot be maintained. In addition, the deterioration of the signal transmission characteristic becomes more notable as the signal transmission speed becomes higher.